The present invention relates to biaxially textured metallic substrates and articles made therefrom, and more particularly to such substrates and articles made from high purity face-centered cubic (FCC) materials using powder metallurgy techniques to form long lengths of biaxially textured sheets, and more particularly to the use of said biaxially textured sheets as templates to grow epitaxial metal/alloy/ceramic layers.
Current materials research aimed at fabricating high-temperature superconducting ceramics in conductor configurations for bulk, practical applications, is largely focused on powder-in-tube methods. Such methods have proved quite successful for the Bixe2x80x94(Pb)xe2x80x94Srxe2x80x94Caxe2x80x94Cuxe2x80x94O (BSCCO) family of superconductors due to their unique mica-like mechanical deformation characteristics. In high magnetic fields, this family of superconductors is generally limited to applications below 30K. In the Rexe2x80x94Baxe2x80x94Cuxe2x80x94O (ReBCO, Re denotes a rare earth element), Tlxe2x80x94(Pb,Bi)xe2x80x94Srxe2x80x94(Ba)xe2x80x94Caxe2x80x94Cuxe2x80x94O and Hgxe2x80x94(Pb)xe2x80x94Srxe2x80x94(Ba)xe2x80x94Caxe2x80x94Cuxe2x80x94O families of superconductors, some of the compounds have much higher intrinsic limits and can be used at higher temperatures.
It has been demonstrated that these superconductors possess high critical current densities (Jc) at high temperatures when fabricated as single crystals or in essentially single-crystal form as epitaxial films on single crystal substrates such as SrTiO3 and LaAlO3. These superconductors have so far proven intractable to conventional ceramics and materials processing techniques to form long lengths of conductor with Jc comparable to epitaxial films. This is primarily because of the xe2x80x9cweak-linkxe2x80x9d effect.
It has been demonstrated that in ReBCO, biaxial texture is necessary to obtain high transport critical current densities. High Jcxe2x80x2s have been reported in polycrystalline ReBCO in thin films deposited on special substrates on which a biaxially textured non-superconducting oxide buffer layer is first deposited using ion-beam assisted deposition (IBAD) techniques. IBAD is a slow, expensive process, and difficult to scale up for production of lengths adequate for many applications.
High Jc""s have also been reported in polycrystalline ReBCO melt-processed bulk material which contains primarily small angle grain boundaries. Melt processing is also considered too slow for production of practical lengths.
Thin-film materials having perovskite-like structures are important in superconductivity, ferroelectrics, and electro-optics. Many applications using these materials require, or would be significantly improved by, single crystal, c-axis oriented perovskite-like films grown on single-crystal or highly aligned metal or metal-coated substrates.
For instance, Yxe2x80x94Ba2xe2x80x94Cu3xe2x80x94Ox (YBCO) is an important superconducting material for the development of superconducting current leads, transmission lines, motor and magnetic windings, and other electrical conductor applications. When cooled below their transition temperature, superconducting materials have no electrical resistance and carry electrical current without heating up. One technique for fabricating a superconducting wire or tape is to deposit a YBCO film on a metallic substrate. Superconducting YBCO has been deposited on polycrystalline metals in which the YBCO is c-axis oriented, but not aligned in-plane. To carry high electrical currents and remain superconducting, however, the YBCO films must be biaxially textured, preferably c-axis oriented, with essentially no large-angle grain boundaries, since such grain boundaries are detrimental to the current-carrying capability of the material. YBCO films deposited on polycrystalline metal substrates do not generally meet this criterion.
The present invention provides a method for fabricating biaxially textured sheets of alloy substrates with desirable compositions. This provides for applications involving epitaxial devices on such alloy substrates. The alloys can be thermal expansion and lattice parameter matched by selecting appropriate compositions. They can then be processed according to the present invention, resulting in devices with high quality films with good epitaxy and minimal microcracking.
The terms xe2x80x9cprocessxe2x80x9d, xe2x80x9cmethodxe2x80x9d, and xe2x80x9ctechniquexe2x80x9d are used interchangeably herein.
For further information, refer to the following publications:
1. K. Sato, et al., xe2x80x9cHigh-Jc Silver-Sheathed Bi-Based Superconducting Wiresxe2x80x9d, IEEE Transactions on Magnetics, 27 (1991) 1231.
2. K. Heine, et al., xe2x80x9cHigh-Field Critical Current Densities in Bi2Sr2Ca1Cu2O8+x/Ag Wiresxe2x80x9d, Applied Physics Letters, 55 (1991) 2441.
3. R. Flukiger, et al., xe2x80x9cHigh Critical Current Densities in Bi(2223)/Ag tapesxe2x80x9d, Superconductor Science and Technology 5, (1992) S61.
4. D. Dimos et al., xe2x80x9cOrientation Dependence of Grain-Boundary Critical Currents in Y1Ba2Cu3O7xe2x88x92* Bicrystalsxe2x80x9d, Physical Review Letters, 61 (1988) 219.
5. D. Dimos et al., xe2x80x9cSuperconducting Transport Properties of Grain Boundaries in Y1Ba2Cu3O7 Bicrystalsxe2x80x9d, Physical Review B, 41 (1990) 4038.
6. Y. Iijima, et al., xe2x80x9cStructural and Transport Properties of Biaxially Aligned YBa2Cu3O7xe2x88x92x Films on Polycrystalline Ni-Based Alloy with Ion-Beam Modified Buffer Layersxe2x80x9d, Journal of Applied Physics, 74 (1993) 1905.
7. R. P. Reade, et al. xe2x80x9cLaser Deposition of biaxially textured Yttria-Stabilized Zirconia Buffer Layers on Polycrystalline Metallic Alloys for High Critical Current Yxe2x80x94Baxe2x80x94Cuxe2x80x94O Thin Filmsxe2x80x9d, Applied Physics Letters, 61 (1992) 2231.
8. D. Dijkkamp et al., xe2x80x9cPreparation of Yxe2x80x94Baxe2x80x94Cu Oxide Superconducting Thin Films Using Pulsed Laser Evaporation from High Tc Bulk Material,xe2x80x9d Applied Physics Letters, 51, 619 (1987).
9. S. Mahajan et al., xe2x80x9cEffects of Target and Template Layer on the Properties of Highly Crystalline Superconducting a-Axis Films of YBa2Cu3O7xe2x88x92x by DC-Sputtering,xe2x80x9d Physica C, 213, 445 (1993).
10. A. Inam et al., xe2x80x9cA-axis Oriented Epitaxial YBa2Cu3O7xe2x88x92xxe2x80x94PrBa2Cu3O7xe2x88x92x Heterostructures,xe2x80x9d Applied Physics Letters, 57, 2484 (1990).
11. R. E. Russo et al., xe2x80x9cMetal Buffer Layers and Yxe2x80x94Baxe2x80x94Cuxe2x80x94O Thin Films on Pt and Stainless Steel Using Pulsed Laser Deposition,xe2x80x9d Journal of Applied Physics, 68, 1354 (1990).
12. E. Narumi et al., xe2x80x9cSuperconducting YBa2Cu3O6.8 Films on Metallic Substrates Using In Situ Laser Deposition,xe2x80x9d Applied Physics Letters, 56, 2684 (1990).
13. R. P. Reade et al., xe2x80x9cLaser Deposition of Biaxially Textured Yttria-Stabilized Zirconia Buffer Layers on Polycrystalline Metallic Alloys for High Critical Current Yxe2x80x94Baxe2x80x94Cuxe2x80x94O Thin Films,xe2x80x9d Applied Physics Letters, 61, 2231 (1992).
14. J. D. Budai et al., xe2x80x9cIn-Plane Epitaxial Alignment of YBa2Cu3O7xe2x88x92x Films Grown on Silver Crystals and Buffer Layers,xe2x80x9d Applied Physics Letters, 62, 1836 (1993).
15. T. J. Doi et al., xe2x80x9cA New Type of Superconducting Wire; Biaxially Oriented Tl1(Ba0.8Sr0.2)2Ca2Cu3O9 on {100} less than 100 greater than  Textured Silver Tape,xe2x80x9d Proceedings of 7th International Symposium on Superconductivity, Fukuoka, Japan, Nov. 8-11, 1994.
16. D. Forbes, Executive Editor, xe2x80x9cHitachi Reports 1-meter Tl-1223 Tape Made by Spray Pyrolysisxe2x80x9d, Superconductor Week, Vol. 9, No. 8, Mar. 6, 1995.
17. Recrystallization, Grain Growth and Textures, Papers presented at a Seminar of the American Society for Metals, Oct. 16 and 17, 1965, American Society for Metals, Metals Park, Ohio.
Accordingly, it is an object of the present invention to provide new and useful biaxially textured metallic substrates and articles made therefrom.
It is another object of the present invention to provide such biaxially textured metallic substrates and articles made therefrom by rolling and recrystallizing high purity face-centered cubic materials to form long lengths of biaxially textured sheets.
It is yet another object of the present invention to provide for the use of said biaxially textured sheets as templates to grow epitaxial metal/alloy/ceramic layers. Further and other objects of the present invention will become apparent from the description contained herein.
In accordance with one aspect of the present invention, the foregoing and other objects are achieved by a biaxially textured alloy article having a magnetism less than pure Ni which comprises a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of binary mixtures consisting of: between 99 at % and 80 at % Ni powder and between 1 at % and 20 at % Cr powder; between 99 at % and 80 at % Ni powder and between 1 at % and 20 at % W powder; between 99 at % and 80 at % Ni powder and between 1 at % and 20 at % V powder; between 99 at % and 80 at % Ni powder and between 1 at % and 20 at % Mo powder; between 99 at % and 60 at % Ni powder and between 1 at % and 40 at % Cu powder; between 99 at % and 80 at % Ni powder and between 1 at % and 20 at % Al powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100} less than 100 greater than  orientation texture; and further having a Curie temperature less than that of pure Ni.
In accordance with a second aspect of the present invention, the foregoing and other objects are achieved by a biaxially textured alloy article having a magnetism less than pure Ni which comprises a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of ternary mixtures consisting of: Ni powder, Cu powder, and Al powder; Ni powder, Cr powder, and Al powder; Ni powder, W powder and Al powder; Ni powder, V powder, and Al powder; Ni powder, Mo powder, and Al powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100} less than 100 greater than  orientation texture; and further having a Curie temperature less than that of pure Ni.
In accordance with a third aspect of the present invention, the foregoing and other objects are achieved by a biaxially textured alloy article alloy article having a magnetism less than pure Ni which comprises a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100} less than 100 greater than  orientation texture; and further having a Curie temperature less than that of pure Ni.
In accordance with a fourth aspect of the present invention, the foregoing and other objects are achieved by a strengthened, biaxially textured alloy article having a magnetism less than pure Ni which comprises a rolled and annealed, compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: Ni, Ag, Agxe2x80x94Cu, Agxe2x80x94Pd, Nixe2x80x94Cu, Nixe2x80x94V, Nixe2x80x94Mo, Nixe2x80x94Al, Nixe2x80x94Crxe2x80x94Al, Nixe2x80x94Wxe2x80x94Al, Nixe2x80x94Vxe2x80x94Al, Nixe2x80x94Moxe2x80x94Al, Nixe2x80x94Cuxe2x80x94Al; and at least one fine powder such as but not limited to Al2O3, MgO, YSZ, CeO2, Y2O3, and YSZ; the article having a grain size which is fine and homogeneous and further having a dominant cube oriented {100} less than 100 greater than  orientation texture; and further having a Curie temperature less than that of pure Ni.